Emilie Laverge / CRC16 Featured

Implementation of CRC16 using polynomial 0x8005 - (X^16+X^15+X^2+1)

Dependents:   HC05 S5info_APP4

cyclic redundancy check

A cyclic redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to raw data. Blocks of data entering these systems get a short check value attached, based on the remainder of a polynomial division of their contents; on retrieval the calculation is repeated, and corrective action can be taken against presumed data corruption if the check values do not match.

[source:http://en.wikipedia.org/wiki/Cyclic_redundancy_check]

This class implements a basic CRC16 (17Bits) using polynomial 0x8005 (X^16 + X^15 + X^2 +1).

How to use this library

basic use of CRC 16t

    char testdata[]= "123456789";    
    CRC16 *myCRC = new CRC16();
    unsigned short resultCRC = myCRC->calculateCRC16(testdata,9); //9 is the length of the character array //
    pc.printf("%x",resultCRC);

Files at this revision

API Documentation at this revision

Revision 0:585ead300cab, committed 2014-02-12

Comitter:
EmLa
Date:
Wed Feb 12 21:34:53 2014 +0000
Commit message:
CRC16 implementation; 123456789 --> 0xFEE8

Changed in this revision

CRC16.cpp Show annotated file Show diff for this revision Revisions of this file
CRC16.h Show annotated file Show diff for this revision Revisions of this file 
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/CRC16.cpp	Wed Feb 12 21:34:53 2014 +0000
@@ -0,0 +1,49 @@
+#include "CRC16.h"
+CRC16::CRC16()
+{
+    unsigned short crc16table[256] = { 
+        0x0000, 0x8005, 0x800F, 0x000A, 0x801B, 0x001E, 0x0014, 0x8011,
+        0x8033, 0x0036, 0x003C, 0x8039, 0x0028, 0x802D, 0x8027, 0x0022,
+        0x8063, 0x0066, 0x006C, 0x8069, 0x0078, 0x807D, 0x8077, 0x0072,
+        0x0050, 0x8055, 0x805F, 0x005A, 0x804B, 0x004E, 0x0044, 0x8041,
+        0x80C3, 0x00C6, 0x00CC, 0x80C9, 0x00D8, 0x80DD, 0x80D7, 0x00D2,
+        0x00F0, 0x80F5, 0x80FF, 0x00FA, 0x80EB, 0x00EE, 0x00E4, 0x80E1,
+        0x00A0, 0x80A5, 0x80AF, 0x00AA, 0x80BB, 0x00BE, 0x00B4, 0x80B1,
+        0x8093, 0x0096, 0x009C, 0x8099, 0x0088, 0x808D, 0x8087, 0x0082,
+        0x8183, 0x0186, 0x018C, 0x8189, 0x0198, 0x819D, 0x8197, 0x0192,
+        0x01B0, 0x81B5, 0x81BF, 0x01BA, 0x81AB, 0x01AE, 0x01A4, 0x81A1,
+        0x01E0, 0x81E5, 0x81EF, 0x01EA, 0x81FB, 0x01FE, 0x01F4, 0x81F1,
+        0x81D3, 0x01D6, 0x01DC, 0x81D9, 0x01C8, 0x81CD, 0x81C7, 0x01C2,
+        0x0140, 0x8145, 0x814F, 0x014A, 0x815B, 0x015E, 0x0154, 0x8151,
+        0x8173, 0x0176, 0x017C, 0x8179, 0x0168, 0x816D, 0x8167, 0x0162,
+        0x8123, 0x0126, 0x012C, 0x8129, 0x0138, 0x813D, 0x8137, 0x0132,
+        0x0110, 0x8115, 0x811F, 0x011A, 0x810B, 0x010E, 0x0104, 0x8101, 
+        0x8303, 0x0306, 0x030C, 0x8309, 0x0318, 0x831D, 0x8317, 0x0312,
+        0x0330, 0x8335, 0x833F, 0x033A, 0x832B, 0x032E, 0x0324, 0x8321,
+        0x0360, 0x8365, 0x836F, 0x036A, 0x837B, 0x037E, 0x0374, 0x8371,
+        0x8353, 0x0356, 0x035C, 0x8359, 0x0348, 0x834D, 0x8347, 0x0342,
+        0x03C0, 0x83C5, 0x83CF, 0x03CA, 0x83DB, 0x03DE, 0x03D4, 0x83D1,
+        0x83F3, 0x03F6, 0x03FC, 0x83F9, 0x03E8, 0x83ED, 0x83E7, 0x03E2,
+        0x83A3, 0x03A6, 0x03AC, 0x83A9, 0x03B8, 0x83BD, 0x83B7, 0x03B2,
+        0x0390, 0x8395, 0x839F, 0x039A, 0x838B, 0x038E, 0x0384, 0x8381,
+        0x0280, 0x8285, 0x828F, 0x028A, 0x829B, 0x029E, 0x0294, 0x8291,
+        0x82B3, 0x02B6, 0x02BC, 0x82B9, 0x02A8, 0x82AD, 0x82A7, 0x02A2,
+        0x82E3, 0x02E6, 0x02EC, 0x82E9, 0x02F8, 0x82FD, 0x82F7, 0x02F2,
+        0x02D0, 0x82D5, 0x82DF, 0x02DA, 0x82CB, 0x02CE, 0x02C4, 0x82C1,
+        0x8243, 0x0246, 0x024C, 0x8249, 0x0258, 0x825D, 0x8257, 0x0252,
+        0x0270, 0x8275, 0x827F, 0x027A, 0x826B, 0x026E, 0x0264, 0x8261,
+        0x0220, 0x8225, 0x822F, 0x022A, 0x823B, 0x023E, 0x0234, 0x8231,
+        0x8213, 0x0216, 0x021C, 0x8219, 0x0208, 0x820D, 0x8207, 0x0202};
+ }
+ CRC16::~CRC16()
+ {}
+unsigned short CRC16::calculateCRC16(char input[], int lenght)
+{
+    unsigned short CRC16 = 0;
+    for(int i = 0; i < lenght; i++)
+    {
+        unsigned  short tableValue = crc16table[((CRC16>>8)^*(char *)input++)&SHIFTER];
+        CRC16=(CRC16<<8)^tableValue;
+    }
+    return CRC16;
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/CRC16.h	Wed Feb 12 21:34:53 2014 +0000
@@ -0,0 +1,15 @@
+#ifndef CRC16_H
+#define CRC16_H
+
+class CRC16
+{
+    private:
+    const unsigned int SHIFTER = 0x00FF;
+    unsigned short crc16table[256];
+    
+    public:
+    unsigned short calculateCRC16(char input[], int lenght);
+    CRC16();
+    ~CRC16();
+};
+#endif
\ No newline at end of file